Evolution and humans: big brain size uses energy (Evolution)

by dhw, Saturday, November 04, 2017, 13:32 (443 days ago)@ David Turell

DAVID: No self-respecting ape type leaves the trees without a reason. There is evidence of upright posture alterations in the spine 23 million years ago, in preparation for the descent. If they came out of the trees as you propose, there should be more fossil evidence of the pelvic alterations required. There are none. The speciation gap exists.
dhw: And why should there be more fossils of pelvic alterations after descent than there are of pelvic alterations in anticipation of descent?
DAVID: Lucy walked fully upright at the start with pelvic lumbar spine changes in place. Fossils are few and far between with early hominins. Lucy is the closest thing we have to an ape-human in-between. We don't know when Lucy in her forbears achieved her form. In trees or down.

You were talking about a fossil from 23 million years ago with spinal changes which you think your God must have engineered "in preparation" before the ape descended from the trees. Now you tell me we don’t even know if the 3.2-million-year-old Lucy “achieved her form” before or after she descended, and you have not told me why there should be more fossils if the 23-million-year-old’s anatomy changed after it had descended from the trees. Yes indeed, fossils are few and far between. So how does that prove that your God must have dabbled BEFORE early hominins descended?

Dhw: Once the brain had reached optimum size, complexity took over from enlargement. The efficiency of complexification would then eventually have led to less volume. Nobody knows the cause of enlargement (hence hypotheses concerning diet, upright posture, cooking, random mutations, divine dabbling), but since we KNOW that new concepts RESULT in rewiring/complexification, it is not unreasonable to suggest that in earlier times new concepts RESULTED in expansion.
DAVID: It is unreasonable since the only event we have seen is shrinkage in an established size of brain in an large skull. How does the skull decided to enlarge if the brains says to itself I'm enlarging, so it tells the skull, "skull get bigger"? Note the need for advanced planning, which you like to forget. I repeat: shrinkage is epigenetic, enlargement must be speciation.

If shrinkage is epigenetic (i.e. does not require a divine dabble), then the brain cells are cooperating to make the changes. (You agree that “the brain does it on its own”). The same process would apply with enlargement, as the different cell communities cooperate, just as they do whenever organisms adapt. I don’t “forget” the need for advanced planning: I challenge that whole assumption. In my hypothesis, adaptation and speciation follow the same course, and are often connected, as they RESPOND to challenges and opportunities. The skull adapts to contain the expanding brain it houses; the leg adapts to its new maritime environment and becomes a fin; the hominin spine adapts to the new demands of life on the ground. If God can create a mechanism that enables the brain to shrink on its own, why do you think the same mechanism is incapable of making the brain expand, and is incapable of making the skull adapt to the expansion?

dhw: As a matter of interest, do your ID friends insist that their God fiddled with ape anatomy before apes left the trees, designed eight stages of pre-whales before they entered the water, and planned weaverbird’s nests, toxin-swallowing snakes and skull shrinking shrews in order to keep life going until he could produce Homo sapiens’ brain? A simple yes or no will do.
DAVID: Generally, yes. They believe in planning and design.

Of course intelligent design believers believe in planning and design. It’s the details of your divinely controlled evolutionary history I’m asking about. Do they insist, for instance, that their God dabbled with ape anatomy before apes left the trees?